When a still picture is sent through a transmission medium such as an ISDN (Integrated Service Digital Network) line, the sender side performs a picture compressing process for the still picture and the receiver side performs a picture decompressing process for the received signal so as to restore the original still picture.
However, when picture data that is sent through a transmission medium whose transmission rate is not sufficiently high such as an ISDN line is received by a receiving apparatus and supplied to a video signal recording apparatus such as a DVCR (Digital Video Cassette Recorder), the receiving apparatus cannot sufficiently supply the picture signal to the DVCR. In the worst case, a decoding error may take place in the DVCR.
In addition, it takes around 13.5 seconds to send one frame of still picture through the ISDN line. Thus, when picture data is retrieved from for example a database connected to the ISDN line, it takes a long time to determine whether or not the received picture is a desired picture.